Basic

• The basic silicon tetrahedron, SiO4, has one silicon atom in the middle with four oxygen atoms surrounding it. If you draw straight lines from each of the oxygen atoms, the shape of a tetrahedron appears as triangles on each side. One oxygen atom sits on top of the tetrahedron where all the points meet while the other three form the corners of the triangles.
  
  

Chains

• The pyroxene group of minerals contains the silicon tetrahedron in chains. An example of a pyroxene is diopside, or CaMgSi2O6. Each tetrahedron in the single chain is connected to the next one at a corner, with each tetrahedron sharing two of the oxygen atoms from the adjoining structure. This creates a long single chain.
  
  

Double Chains

• Double chains, such as amphiboles, use the same structure as single chains with the exception that a third oxygen atom is shared. Hornblende is the most abundant form of amphibole -- a black mineral found in igneous rocks.
  
  

Sheets

• Each tetrahedron shares three of its oxygen atoms with another tetrahedron in the sheet arrangement. The unshared atom points in the same direction in each tetrahedron on a sheet. Silicon tetrahedrons stack on top of each other, like sheets of a substance.
  
  

Framework

• The framework arrangement takes the basic arrangement and then connects each tetrahedron to another at the corner in a continuous 3D structure. Examples of this arrangement are quartz and feldspar.